Questions tagged [electromagnetic-induction]

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Current induced from a changing magnetic field

This question is motivated by Problem 7.12 in Griffiths Electrodynamics book. I have already solved the question, so there is no issue with homework policy. Relevant Equations: $$\Phi = \int{\vec{B}\...
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25 views

Inductors in Transformers

Why is it the flux change which induces the ac current of primary coil equal to the flux change that primary coil induces on the secondary coil? Is it possible to prove this? slide from video ...
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32 views

Can one measure the current in a ferromagnet?

I understand that all magnetic fields are the result of current (charges in motion). I'm now doing research on electromagnetic induction and understand that changing magnetic flux will induce a ...
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Is magnetic flux depending on the orientation of ferromagnetic rotor?

I have attached a picture of Reluctance motor setup. When I turn on the AC source, Magnetic flux lines will build up. My question is, will the magnetic flux will be a function of the angle turned by ...
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20 views

Direction of induced current [on hold]

In the image, the loop ABCD is moving away from the current carrying straight wire. I am just confused about the direction of induced current in the loop. The book shows that the current is anti-...
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Time varying magnetic field and induced electric field

Well I would like to start with asking few questions for you to provide a detailed solution and whose details has been clearly mentioned in the above image. It would be helpful if you could clearly ...
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7 views

Induced Electric Field due to Infintely spread out, changing magnetic field

If I have a uniform, downward pointing magnetic field which is spread across a very large region and the magnitude of the magnetic field is increasing with time, what is the shape of the induced ...
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13 views

Force on a stationary negatively charged conductor in a changing field

If a magnet is brought near a conductor it induces a current in it caused by the movement of free electrons which behave like tiny magnets. But if a magnet exerts a force of attraction on the ...
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Magnetism in moving charges and induced emf [duplicate]

Why is electric field produced by varying magnetic field on metal non-conservative?
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Moving iron rod through solenoid [closed]

What effect(s) does a moving iron rod have on a solenoid? Which of the graphs is correct?
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8 views

Correlation between the radius of a cylindrical coil with the curl of the electric field induced in that coil

A background of the lab, I am currently working on: I have different sizes of cylindrical coil of wire, each with different radius. I then pass the coil through a near uniform magnetic field and then ...
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Magnetic field induction from an electric current through molten metal and from an electron beam?

The flow of electrons through a wire induces a magnetic field around the wire. To me it is not possible to distinguish between two possible scenario: Switching on a current the currents electrons get ...
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1answer
19 views

Finding direction of induced EMF

How should I find out the direction of the EMF induced in a rod of any length $l$ rotating with an angular speed $w$ in a region of magnetic field (perpendicular to the plane of the rotating rod) ...
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Why the electric field induced in the $\phi$ component, non-zero as compared to the $s$ and $z$ which are zero?

If we take a coil in a uniform magnetic field, move it around to induced some emf around the coil. And so in order to calculate the curl of the electric field induced in cylindrical coordinate system, ...
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2answers
67 views

Explanation of motional EMF in a rod

Why does an EMF generate across a rod moving linearly in a region of magnetic field constant with space and time? While proving it, we considered the rod to be connected to a conducting rectangular ...
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1answer
84 views

Explanation of rotational EMF

Why does an EMF $\frac{1}{2}B\omega R^2$ get created across the radius $R$ of a Faraday's disc when it rotates, with angular velocity $\omega$, in a magnetic field constant with both space and time? ...
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IN 3 phase transformer the winding are 180 degree out of phase and where it is used as application

application of 180 phase shift transformer am a novice in electrical engineering. I notice that in transformer the secondary side current & current referred to as primary are 180 degree out of ...
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25 views

Magnet oscillation with coils

I am trying to conduct an experiment in which I will try to find the natural frequency of a cantilever. To oscillate the cantilever, I thought I could use a magnet and a current-carrying coil wire ...
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2answers
25 views

Electric Field in conductor near Solenoid

My question is essentially a follow up to this question. It's answer says, the mobile charges in the conductor distribute themselves to make E = 0 inside the conductor. But, I don't understand how a ...
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15 views

Question about induced current with an axis parallel to magnetic field

I am currently going over a physics test. One of the questions asked if a square loop of wire perpendicular to a uniform magnetic field entering the page has an induced charge if it is spun ...
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1answer
98 views

Experiment: Magnet falling in a copper/aluminum pipe

We know that when we release a magnet in conducting pipe (aluminum, copper, etc..) it will be subjected to a magnetic force induced by the induced current. This magnetic field will be created in a ...
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7 views

Calculation of eddy currents and subsequent heating in a metal, ATEX-rated junction box

We are building a system which will make use of a stainless steel junction box to connect different circuits within it. This will be located in a hazardous offshore environment so we will be using an ...
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4answers
96 views

Why does inductor current lag the applied voltage at its terminal by 90 degrees?

I studied electromagnetism and I am currently working with Inductors. I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 ...
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1answer
30 views

Magnet moving between $2$ separate coils, connected to a circuit

I was thinking about a question regarding a magnet entering a coil when the following thought came: what if we unravelled the middle of the coil such that it splits into $2$ equal parts, and connected ...
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3answers
142 views

Current in only inductive AC circuit

Current through a LR circuit is given by $$i=i_0 (1-e^{\frac{-tR}{L}})..1$$From here I can observe that as I tend R towards 0 no current flows through the circuit , and current will be 0 when the ...
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2answers
52 views

What is actually being removed when a metal conductor is grounded?

I found this image earlier this morning, and yes, there are a lot of diagrams/illustrations about this, transferring charges by induction has been introduced since the very beginning of high school ...
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1answer
45 views

Does grounding set the potential on a surface of a sphere to $~0~$ or the potential due to the charges of the sphere to $~0~$?

I'm understand that grounding sets the potential to $0$, but I'm confused as to which potential it sets to $0$. Let me explain my question: If I have a sphere and I bring a positive charge near it, a ...
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1answer
40 views

Regarding the use of Ampere's Law

i wanted to calculate $\mathbf{B}$ of these two parallel wires, and i've taken a glance at the correction and i've found out this equation, i tried to understand it but in vain, where do $(x + \frac{d}...
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1answer
29 views

Electric field due to changing uniform magnetic field

I think this could be a misunderstanding on my part , still I want to clarify this.Suppose in a region of boundless expanse, there is a uniform magnetic field which changes at a rate $\frac{d\phi}{dt}$...
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1answer
82 views

How to compute the curl of the electric field, experimentally?

In order to experimentally verify Faraday's law and express the curl of the induced electric field, is there any other way to compute the curl without directly working on the cross product (ie working ...
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32 views

Investigating the relationship between a changing B field and the curl of the electric field induced

I am currently working on a 12 page lab report on Faraday's law, essentially investigating, how for different magnetic field strength through a stationary loop of wire with N number of turns, effects ...
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1answer
32 views

What is $v(t)$ in a sliding conducting rail in a magnetic field?

This is problem 7.7c from David J. Griffiths - Introduction to Electrodynamics. A metal bar of mass $m$ slides frictionlessly on two parallel conducting rails a distance $l$ apart. A resistor $R$ ...
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2answers
105 views

Why doesn't current cancel in a generator?

I am a little confused about the application of Faraday's law in a generator. If we imagine a magnet attached to a wheel (which spins when water falls on it) next to a coil, as the magnet spins around,...
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365 views

How is it possible for the induced emf to take negative values in Faraday's Law of induction?

Faraday's Law of induction states that the work done per unit charge by the (induced) electric force along a loop of wire, or the emf, is minus the rate of change of magnetic flux through the loop/...
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Rate of change of area of a circular loop exiting a uniform magnetic field

The question is to find the variation in induced electromotive force w.r.t to time or put simply $\varepsilon(t)$ for a circular loop being removed from the region of the magnetic field at a constant ...
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Can electricity be generated using a rotating electromagnet and fixed metal plates enclosing it (as opposed to rotating permanent magnet)?

I was wondering , if this be possible , can we make an adjustable electricty generator? If not, why so? Appreciate any responses .
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Potential drop across inductors in DC circuits

The potential drop across an inductor is equal to $L(di/dt)$ where $L$ is inductance coefficient. But according to this in a DC circuit there should be no potential drop across the inductor (because $...
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Quantum Mechanical Treatment of the Spin Echo

I'm trying to find the expectation value of the spin in the $y$ direction after applying a $\pi/2$-$\pi/2$ sequence of pulses. In Slichter's Principles of Magnetic Resonance, he does a $\pi/2$-$\pi$ ...
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How is the magnetic flux density inside a current tube affected by an inner wire?

Background to problem Conventional wisdom informs that the magnetic flux density inside a tube carrying current is zero everywhere. Pictorially this is represented by this finite element analysis (...
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Direction of EMF and Induced current through the circuit

When the circuit shown above is moved with a constant velocity to the left I know that B is going to have the higher potential. And I believe that the current flows clockwise that is in the sense of ...
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What is the main mechanism for induction heaters (cookers)?

I thought that induction heaters (as used in cooking) relied on Joule heating losses due to Eddy currents induced by an oscillating magnetic field, produced by an inductor through which AC runs ...
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72 views

How Is Induction Energy Transferred From a Toroidal Solenoid To An External Conductor During Linear Current Change?

It is widely understood that $\nabla \times \vec A =\vec B = 0$ outside a toroidal solenoid with constant current, $I=k$ ($I = \vec J$ in the below illustration). It is not so widely understood that ...
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48 views

Do magnetic field lines actually cancel?

Typically when explaining why parallel conducting wires attract, it is said that their magnetic fields cancel out (in the case of same direction current) and hence produces an attraction force due to ...
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MHD pump liquid metal flow speed

a rather simple question, are there any studies or some information about the flow speed of liquid metal inside a tube? My setup is basically a 50cm diameter circular tube (could be another diameter) ...
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1answer
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Nature of induced emf in Faraday's law

When there is a battery in a simple circuit loop, for instance, there is a real low potential terminal and a high potential terminal , the battery does work on charges and delivers them at high ...
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60 views

How is the rate of current change in an inductor present in a circuit maintained / decreased?

Considering an ideal circuit of DC voltage source and an inductor connected together with a switch in between them. When the switch is closed at t=0 the current starts increasing which causes induced ...
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A parallel between eddy current and Beer-Lambert law

For AC current flowing in wire eddy currents are the reason for current density decay as we move towards the center. Similarly, in Beer-Lambert law, for electromagnetic plane wave impinging on ...
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1answer
29 views

How can diamagnetism levitate anything?

From the explanation of diamagnetism that I was given, the electrons when exposed to a changing magnetic field will change their spin in accordance to Lenz's law. This will induce an opposing magnetic ...
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Potential due to initially uncharged induced conductor?

From Griffiths' Introduction to electrodynamics: In this problem, Griffiths says that we will set the potential inside and on the surface of the conductor to be zero since its an equipotential ...
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Confusion in understanding the behavior of inductor in RL circuit with DC source

When we have a DC voltage source with a switch in series with $RL$ and the switch is closed at $t=0$ then it is said that current is zero initially, but the voltage across inductor is same as that of ...